Process of treating aluminum-silicate ores.



umrnn STATES. PATENT OFFICE.

FRANK J. TONE, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO THE CARBORUNDUM. COMPANY, OF NIAGARA FALLS, NEW YORK, A CORPORATIIJN OF PENNSYLVANIA.

Specification of Letters Patent.

Patented .nu 27, 190a Application filed my 4, 1909. Seria1No. 493,879.

To all whom it may concern:

Be it known that I, FRANK J. TONE, of.

' Niagara Falls, Niagara county, New York,

have invented a new and useful Process of Treating Aluminum-Silicate Ores, of which the following is a full, clear, and exact description.

My invention relates to the smelting of aluminum silicate ores in electric furnaces.

' In my United States Patent No. 906,172, granted on December 8th, 1908, I described a process of smelting aluminum ores wherein a mixture of aluminum silicate, carbon and base metalliferous material, such as iron oxid, is heated in an electric furnace. -In this process under proper conditions, the

rodu'cts are fused aluminate and silicon aloy. In the use of the said patented process, on account of the high percentage, of silica present in the aluminum silicate, some difficulty has been found in entirely removing the silica by reducin it to silicon and "alloying this silicon with t e metal of a metalliferous material.

'My invention is designed to provide an improved and more easily operated process by which the silica may be more efiectually removed.

To that end, the invention consists in carrying out the smelting in two stages, in the first of which the silica is only partially re- ,duced and in the second of which its reduction is completed.

I will now describeone specific method which I have successfully used in accordance with my invention. A charge is made up consisting of aluminum silicate, iron oxid and carbon in about the following proportions by weight; aluminum silicate, 222 parts; ferric oxi 160 parts; carbon, 60 parts. The proortions of this charge are such that the caron is sufficient to reduce all the iron and about half of the silica. This mixture is char ed into an electric furnace of any type suita 1e for giving a temperature suflicient to reduce the silica in the presence of iron oxid. For this purpose, I have used with good results an electric furnace of the horizontal incandescent type heatedby a central carbon core embedded in the charge. The current is passed through the furnace to an amount suiiicient to heat the mixture to the temperature at which the aluminum silicate is dissociated and the silica is partlally reduced in the presence, of iron, this reduced product remaining more or less in a granular or shotted form scattered throughout the charge. I do not aim to collect this product in a fused mass in the first operation, althoughsilicon iron alloy often does collect and settle in the bottom of the furnace.

Some aluminum carbid and silicon carbid are also incidentally formed. After this partial reduction of the silica, the products are removed from the furnace, and are then mixed with additional carbon and additional iron oxid and subjected to the second step of the process, carried out in an electric furnace. In this second step I preferably use an ordinary form of arc furnace with vertical electrodes dependin into the furnace pot or chamber. The c arge mixture is fed around the electrodes, and the current is passed through the furnace in suflicient uantity to fuse the charge and result in a su stantially complete reduction of all the silica and fusion 'of the alumina. The fused silicon forms an allo with the iron, much of which settles at the ottom of the furnace from which it may be tapped at intervals if desired.

Instead of adding an insufficient quantity of carbon to reduce the silica in the first ste I may add sufiicient carbon to com lete y reduce the silica." But in such case carry the first step only to the point where the silica is only partially reduced. In this case,-

the remaining carbon may appear in the products of the first ste as free carbon, or as aluminum carbid or si icon carbid, or both. In this case the second step is carried on as before, more iron oxid being added to the charge. The iron may be added in the form of finely divided metal instead of the oxid, in either case, in which case the amount of carbon is correspondingly reduced to an amount corresponding to the reduction or partial reduction of the silica.

The advantages of my invention will be apparent to those skilled in the art. Where the silicon is reduced in one operation, the conductivity and fluidity of the fused charge is hi h owing to the larger amounts of carbon and iron oxid. In this case the furnace treatment possesses some difficulty. In the present case, the conductivity of the charge is much lower, due to its lower content of iron also reduced in the two-stage process.

'oxid. The loss of alumina by reduction is cate, which consists in forming a charge of Y it? aluminum silicate, base metalliferous mate-' rial, and carbon, subjecting such charge to electrically developed heat, partially reducing the "silica thereby, and alloying the reduced silicon with the reduced metalliferous material, then increasing the percentage of metalliierous material and subjecting the charge to suflicient electrically developed heat to fuse the alumina, reduce the silica and alloy the silicon with the reduced metalliferous material.

2. The process of treatingaluminum silicate, which consists of forming a charge of aluminum silicate, base metalliferous material, and carbon, subjecting said charge to electrically developed heat sufiicient to dissociate the aluminum silicate, partially reduce the silica and alloy the silicon with reduced metalliferous material, removing the products from the furnace; then forming a second charge of said products and additional metalliferous material, subjecting said second charge to electrically develo ed heat sufiicient to fuse the alumina, comp etely reduce the silica, and alloy the silicon with the reduced metalliferous' material.

3. The process of treating aluminum si1i-' cate, which consists of forming a charge of alu minum silicate, base metalliferous material and carbon, the carbon being in amount suf ficient to reduce only part of the silica, sub-' j ecting said charge to'electrically developed heat sufficient to dissociate the aluminum silicate'partially reduce the silica, and alloy the silicon with the reduced metalliferous material, removing the products from the furnace; then forming a second charge of said products mixed with sufficient carbon and metalliferous material to complete the reduction of the silica and alloy the reduced silicon, subjecting said second charge to electrically developed heat sufficient to fuse the alumina, completely reduce the silica and alloy the siliconwith the reduced metalliferous material.

4. The method of smelting aluminum silicate, consisting in subjecting a charge of aluminum silicate, base metalliferous material, and carbon, to electrically developed heat,

partially reducing the silica, adding further] metalliferous material, and completing the 7 reduction of silica.

In testimony whereof, I have hereunto set my hand.

W. A. DWYER, F. I. 'PIERoE. 

